The present disclosure relates generally to the field of organic synthetic methodology for the preparation of antiviral compounds and their synthetic intermediates.
Positive-single stranded RNA viruses comprising the Retroviridae family include those of the subfamily Orthoretrovirinae and genera Alpharetrovirus, Betaretrovirus, Gammaretrovirus, Deltaretrovirus, Epsilonretrovirus, Lentivirus, and Spumavirus which cause many human and animal diseases. Among the Lentivirus, HIV-1 infection in humans leads to depletion of T helper cells and immune dysfunction, producing immunodeficiency and vulnerability to opportunistic infections. Treating HIV-1 infections with highly active antiretroviral therapies (HAART) has proven to be effective at reducing viral load and significantly delaying disease progression (Hammer, S. M., et al.; JAMA 2008, 300: 555-570). However, these treatments could lead to the emergence of HIV strains that are resistant to current therapies (Taiwo, B., International Journal of Infectious Diseases 2009, 13:552-559; Smith, R. J., et al., Science 2010, 327:697-701). Therefore, there is a pressing need to discover and synthesize new antiretroviral agents that are active against emerging drug-resistant HIV variants.
U.S. patent application Ser. No. 15/680,041 discloses novel compounds useful for treating a Retroviridae viral infection, including an infection caused by the HIV virus. One specific compound identified therein is a compound of formula I:

There is currently a need for improved synthetic methods and intermediates that can be used to prepare the compound of formula I and co-crystals, solvates, salts, and combinations thereof. There is also a need for improved methods for preparing intermediate compounds that can be used to prepare the compound of formula I and its co-crystals, solvates, salts, and combinations thereof. The improved methods and intermediates may reduce the cost, time, and/or the amount of waste associated with the existing methods for preparing the compound of formula I and co-crystals, solvates, salts, and combinations thereof.